The present invention relates to a process for shortening the time required for shifting gears in a semi-automatic, electronically controlled motor vehicle transmission by reduction of clutch engagement response time.
A semi-automatic transmission refers generally to a transmission in which the selection of a particular gear by a driver electronically actuates a gear shifting operation, and in which a clutch is selectively disengaged during the shifting of gears by a driver-operated clutch pedal. Generally, in such transmissions, the currently selected gear is calculated by an electronic gear-shifting system for readout on a gear display. A gear shift command emitting device, operable by the driver for selection of a desired gear, transmits a gear-shifting command to the electronic system corresponding to the selected gear. The electronic gear-shifting system also computes an advantageous gear, which is displayed by a blinking indicator on the gear display. Concurrent with selection of a particular gear by operation of the gear-shift command emitting device, the driver must simultaneously disengage the clutch by depressing the clutch pedal. The above-mentioned electronic system then generally switches valves connected to a pressure fluid supply, which subsequently shift corresponding gear shift couplings in the transmission via operating cylinders in such manner that the desired upward or downward shift is properly achieved.
When the shifting process to the newly selected gear is completed, an acknowledgment device is actuated by the electronic gear-shifting system, informing the driver that re-engagement of the clutch is properly warranted. The driver then engages the clutch by releasing the clutch pedal. The acknowledgment device may be optical, acoustic or of other sensory format.
A speed shifting system for a transmission actuated by outside force is disclosed in German Patent DE 30 07 953. The system described therein is provided with a gear shift command emitting device whose lever can be pushed initially into a locking position by the driver. This initiates shifting into a different gear. As soon as this is completed, the clutch lever is released from its locked position by means of a locking pin, permitting the lever to then be swiveled further into an end position. By virtue of this xe2x80x9csensoryxe2x80x9d acknowledgment of the gear shifting action, the driver is informed that he can properly engage the clutch once more, without being distracted by optical or acoustic signals.
A gear shifting apparatus for a synchronized transmission is disclosed in German Patent DE-33 29 802 C2 in which the movement of the sliding bushings of the actuating cylinders or rod systems to which they are connected is detected by means of distance indicators.
A disadvantage of the known arrangements is that the overall time required to shift gears is relatively long, as it includes the reaction time of varying length of the driver of the vehicle for the re-engagement of the clutch.
It is therefore the object of the present invention to propose a process for the shifting of a semi-automatic motor vehicle transmission which shortens the overall shifting time, and thereby also the corresponding duration of force flow interruption occurring during gear shifting.
In accordance with these and other objects of the invention, there is provided a method for shortening a duration required to shift gears applicable for use in a semi-automatic motor vehicle transmission. Such transmission is controlled by an electronic system with a microprocessor, and includes a shifting command emitter for initiating a gear shifting operation. A clutch, further included in the transmission and which is disengaged by the driver when making a gear selection, can only properly be re-engaged following a completion of gear synchronization. An acknowledgment device for emitting an acknowledgment signal to the driver indicating that re-engagement of the clutch may be properly effected is also provided. In accordance with embodiment of the invention, a determination of the beginning of synchronization is made, and the acknowledgment signal is emitted at such time, in advance of complete synchronization.
The invention makes it possible to considerably shorten the overall time required to switch gears independent of the individual driver""s reaction abilities. Contrary to the state of the art, rather than first being emitted upon completed gear shifting action, the acknowledgment signal is sent earlier, when the synchronization begins. The resultant shortening of the period of force flow interruption is especially advantageous when driving up or down an incline, since the speed at which the vehicle travels fluctuates less during the shortened gear-shifting pause.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.